In VBA, False equals zero, but any other number is considered to be True. So testing whether 2 Booleans variables are equal to one another could be equivalent to asking if -1=1.

It is safe to ask if a Boolean <> False

Also, you are using AddCustomInfo. If the part already has a custom property, then AddCustomInfo doesn't work. You need to test if the variable already exists. If so, you need to set it rather than try to add it again.